JPS60127081A - Detector for weld zone by ultrasonic wave - Google Patents

Abstract

PURPOSE:To realize easily automation of a welding machine and to improve the detecting accuracy of a penetration position by moving two ultrasonic probes together with a torch along the weld line and correcting adequately the torch position. CONSTITUTION:Electromagnetic ultrasonic probes 22, 23 are fixed on a traveling base 17. The center of the 1st probe 22 is set right under the welding root part 24 which is the preferable penetration end position of a weld zone 13 and the 2nd probe 23 is disposed in the position spaced from the weld zone 13. Both probes 22, 23 are moved together with a welding torch 21 along the weld line direction between base metals 11 and 12 by the base 17. The detection signal corresponding to the quantity of the reflected echoes inputted from the probes 22, 23 via a flaw detector 25 and the relation stored in an arithmetic processing circuit 26 are compared and the deviation between both is calculated. The program is corrected in accordance with the deviation and the torch 21 is subjected to a playback operation.

Description

Detailed Description of the Invention The present invention is attached to, for example, an automatic welding machine or a welding robot, and works in conjunction with a welding torch to determine the penetration tip position or penetration toe position (hereinafter referred to as "penetration toe position") of a welding part. The present invention relates to a welding part detection device that detects the weld position (hereinafter referred to as "position") using ultrasonic waves.

Generally, when welding a T-joint between two base metals using an automatic welding machine or a welding robot, the welding torch is held along the welding line with one base metal and the other base metal held at right angles. Teaching is performed by moving the welding torch, and then the welding torch is moved along the welding line to perform welding work by operating the play pack according to the teaching contents.

However, in such a teaching-grayback welding method, when the welding line force is small, even if the welding torch operates according to the teaching contents, the position of the welding torch may not be appropriate due to distortion due to welding heat. There is a problem in that it is impossible to form a good welded part because the welding conditions cannot be adapted to the deviation from the normal welding position or the size of the gap between the base materials, variations, etc.

In order to solve these problems, we use an ultrasonic weld detection device that projects ultrasonic waves onto the weld formed between the base metals and detects the penetration position of the weld from the amount of reflected echoes. By detecting the penetration position during welding or immediately after welding with the detection device, the detection result is input to the arithmetic processing device, and the welding torch is operated while adding correction calculations to the teaching contents to form a good weld. It has been known for a long time to do this. τ As the above-mentioned ultrasonic weld detection device, there is a vertical 6 dB drop method using an ultrasonic probe.

Hereinafter, a conventional weld detection device using the vertical 6 dB drop method will be explained with reference to FIGS. 1 to 3.

In FIG. 1, 1 and 2 indicate base materials, and each base material 1.2
are fixed to each other by the welded portion 3, forming a T-joint weld. Reference numeral 4 indicates a vertical ultrasonic probe placed on the base material 1 (hereinafter referred to as "probe 4"), and the probe 4 is, for example, a magnetostrictive vibrator made of a magnetic material and a coil, or a quartz crystal. A piezoelectric vibrator such as a vibrator, an electromagnetic ultrasonic vibrator consisting of a DC electromagnet and a coil, etc. are used, and these are connected to a flaw detection device (not shown). In the figure, 5 indicates a weld root portion which is the welding tip position of the welded portion 3, and 6 indicates a welded toe portion which is the welded contact point between the welded portion 3 and the base metal 1.

In order to detect the penetration amount of the weld 3 using such a weld detection device, when an ultrasonic wave is generated from the probe 4, this ultrasonic wave moves inside the base metal 1 as indicated by the arrow in FIG. The light travels in the same direction, is reflected by the bottom surface of the base material 1, and is then received by the probe 4. Now, let A be the position where the probe 4 is away from the welding part 3, and
The amount of reflected echo when located at is characteristic 7 in Figure 2.
As shown in A, it is assumed that there are < W people. Next, when the probe 4 is gradually moved from this position A toward the welding root section 5 in the direction of the arrow, the amount of reflected echoes decreases and the probe 4 moves toward the welding root section 5. When it comes to the position B corresponding to
A decreases to A (-6 dB).

That is, by moving the probe 4 from an appropriate position A in the direction of the arrow in FIG. 1 and searching for a place where the amount of reflected echo is W^/2, the position of the welding root portion 5 can be detected. This detection method is conventionally known as the vertical 6 dB drop method.
Ru. On the other hand, when detecting the weld toe 6, the probe 4
may be moved in the direction of the arrow from an appropriate position wC shown by a dotted line in FIG. 1 to a position 1j7D corresponding to the weld toe 6. In this case as well, the amount of reflected echo is characteristic 7 in Figure 2.
c changes to 7D, and the reflected echo amount wD becomes Wc/2, so the bath contact end 6 can be detected.

However, in order to continuously detect the position of the weld root portion 5 in the weld line direction using the weld detection device using the vertical 6 dB drop method described above, the probe 4 must be scanned in a zigzag pattern as shown in FIG. In other words, in FIG. 3(A), 8A, 8B, . . . , 8E indicate the intersections with the welding line 9 along the welding root portion 5, and each of the intersections 8A, 8Bt, . . . 8
E can be obtained by moving the base material 1 and the probe 4 relative to each other and scanning the probe 4 across the welding line 9 in a zigzag manner as shown. Therefore, the third
In the figure, the position where the probe 4 is placed on the base material 1 (the bending point that scans in a zigzag manner) corresponds to position A in Figure 1, and the intersection point 8A
+8Bt...8E often corresponds to position B in FIG.

However, consider a case where the welding part detection device including the probe 4 described above is applied to an automatic welding machine or a welding robot.

In this case, as shown in Fig. 3, the probe 4 is moved relative to the base metal 1 and jig-puggled to automatically detect the position of the welding root 5 during or immediately after welding. The detection signal is input from the flaw detection device to the arithmetic processing device, and by making corrections to the teaching content, it is fed back to the welding torch, and the welding portion 3 is continuously formed while controlling the position of the welding root portion 5. .

However, in the prior art described above, the welding work is performed while scanning the probe 4 in a zigzag pattern.
It has the following drawbacks: First, the probe 4 moves in a zig-pug manner in response to the linear movement of the welding torch, so in order for the probe 4 to follow the movement of the welding torch, it is necessary to We need to increase the speed of
Since the operation is complicated, the structure of automatic welding machines, welding robots, etc. is complicated and it is difficult to automate it, which is a drawback. Second, continuous weld line 9
However, it is actually the intersection 8A that can be detected.

Because it becomes an intermittent point such as 8B, ... 8E,
The disadvantage is that highly accurate position detection cannot be performed. Thirdly, when teaching the welding torch and the probe 4, the movements are complicated, so that high-precision h-teaching is difficult to handle and the workability is poor.

The present invention was made in view of the above-mentioned drawbacks of the prior art, and makes it possible to make the welding torch and probe move in the same manner along the welding line, thereby easily realizing automation of the welding machine. Another object of the present invention is to provide an ultrasonic weld detection device that can improve the detection accuracy of the penetration position during handling.

In order to achieve the above object, the features of the configuration adopted by the present invention are as follows. comprising a second ultrasonic probe and a moving means for moving each of the ridge probes together with a welding torch along the welding line direction between the base materials;
A first probe of each of the probes is disposed at a position facing the weld in a molten state, and a second probe is disposed at a position facing the base metal separated from the weld. It's what I did.

Hereinafter, the case where the present invention is applied to an automatic welding machine or a welding robot will be explained based on the embodiments shown in Figs. 4 to 6.

First, in FIG. 4, 11 is a base material fixed to a horizontal pedestal (not shown), 12 is a base material fixed to a vertical pedestal (not shown), and 13 is a space between the base materials 11 and 12. Shows welds. Reference numeral 14 indicates an automatic welding machine or a welding robot to which the present invention is applied (hereinafter referred to as "automatic welding machine 14"), and the automatic welding machine 14 has a support stand 15 located at the lowest position and a A traveling device 1 which is installed in the welding line and can travel in the direction of the welding line (direction orthogonal to the plane of the paper in FIG. 4) by means of hydraulics, electric power, etc.
6, a traveling base 17 located below the base material 11 and fixedly provided on the traveling device 16, and an L-shaped guide 18 erected on the traveling base 17. ing.

A bracket 19 provided on the lower surface of the traveling base 17
A tension spring 2o is tensioned between the guide 18 and the traveling device]6, and biases the traveling platform F to the right in the figure.
The tip portion 18A of the base material 12 is configured to be in close contact with the left side surface 12A of the base material 12. In the figure, 21 is a welding torch for forming a welded part 13 along a welding line, and this welding torch 2
1 is attached to a guide 18, and is configured to be able to rotate in the direction of the arrow in FIG. The position of can be corrected to an appropriate position.

Further, 22.23 indicates an electromagnetic ultrasonic probe as a probe used in the present invention, and each electromagnetic ultrasonic probe 22.23
is fixedly mounted on the traveling base 17 mentioned above.

That is, one of the electromagnetic ultrasonic probes 22 and 23 serves as a first probe,
The center of the probe 22 is located directly under the base material 11 at a distance h-p from the left side surface 11A of the base material 11, that is, at the weld root portion 24, which is the desired penetration tip position of the weld 13. is set directly below. Note that the distance is set to a distance corresponding to a desired penetration amount.

Also, the second 'F! This is the probe of the L-magnetic ultrasonic magnetic probe 23, and the probe 23 is located directly below the base material 11 at a position away from the welding part 13, for example, to the right of the first probe 22. placed on both sides.

Here, the electromagnetic ultrasonic probes 22 and 23 are equipped with a DC electromagnet that applies a magnetic field to the base material 11, and a high frequency wave is applied with the magnetic field applied to the base material 11. and a transmitting/receiving coil that receives the reflected echo as a voltage signal. Then, when each of the probes 22 and 23 applies a magnetic field to the base material 11 with its DC electromagnet and the transmitter/receiver coil is excited with a high frequency pulse, an eddy current flows on the surface of the base material 11. 7. Lorentz force based on Lemming's left-hand rule acts on the base material 11, and mechanical displacement (ultrasonic waves) is generated. This ultrasonic wave propagates perpendicularly from the surface of the base material 11, is reflected at the bottom surface of the base material 11, and returns to the surface side again, so the returned ultrasonic wave is passed through the transmitter/receiver coil through the reverse process of generation, and is then converted into a voltage signal. It has the function of being able to receive as

Furthermore, 25 is a flaw detection device, and the flaw detection device 25 includes each probe. 22. It consists of a DC power supply that applies DC current to the DC electromagnet in 23, a pulse generator that supplies high-frequency pulses to the transmitting and receiving coils, an amplifier that amplifies the voltage signal input from the receiving coil, etc.

On the other hand, reference numeral 26 denotes an arithmetic processing unit provided at the next stage of the flaw detection device 25. A program according to the teaching contents is stored in the arithmetic processing unit 26, and the automatic welding machine 14 and the welding torch 21 are operated according to the program. In addition to having a function to perform backward operation, the arithmetic processing unit 26 stores a function corresponding to the bottom echo level, which will be described later, and calculates the deviation between the detection signal input from the flaw detection device 25 and the function, and calculates the deviation between the detection signal input from the flaw detection device 25 and the function. By making corrections to the program, a feedback operation is performed so that the weld 1-te 21 is always at the optimum position, and the weld 13 is formed along the weld root 24.

Although the present invention is configured as described above, the amount of reflected echoes of the ultrasonic waves received by the electromagnetic ultrasonic probes 22 and 23 is as shown in FIG. That is, all the ultrasonic waves transmitted from the second probe 23 are always directed to the upper surface side of the base material 11 in the figure (
Since the reflected echoes are reflected from the bottom surface), the amount of reflected echoes Wa becomes constant as shown by characteristic 2711 in the figure. On the other hand, if the penetration tip position of the welding part 13 is in the weld root part 24 and is a desirable penetration position, the amount of reflected echoes by the first probe 22 is as shown in characteristic 27b.
According to the principle of the vertical 6 dB drop method, the amount of reflected echo has the relationship Wb=%HWa.

Furthermore, when the welding part 13 does not reach the welding root part 24, the amount of ultrasonic waves reflected from the upper surface of the base material 11 increases, so the amount of reflected echoes Wc received by the first probe 22 is Characteristic 27, C, becomes larger than the above-mentioned Wb. On the other hand, if the welding part 13 penetrates a little too far beyond the position of the welding root part 24, the amount of reflected echoes Wd at that time becomes as shown in the characteristic 27d, and the above-mentioned Wb,! Rainbows also become smaller. In this way, by knowing the relationship between the amount of reflected echoes wb, -Wd from the first probe 22 with respect to the reflected echo MWa of the second probe 230, a desirable penetration position can be detected. be able to.

Next, the reflected echo l in the vicinity of the welded portion 13 was determined by an experimental method as shown in FIG. 6(a). That is, as shown in FIG. 6(a), the sixth
The characteristics shown in Figure ←) were obtained. Here, the transmitting/receiving coil 28 was made of a wire with a wire diameter of 0.16 coils wound spirally up to 20 rIm. In Figure 6), the horizontal axis indicates the center position of the transmitting/receiving coil 28, and the vertical axis indicates the bottom echo level at that time.
(This corresponds to the reflected echo amount Wa in FIG. 5). As a result, the transmitting/receiving coil 28 approaches the welding root portion 24, and the transmitting/receiving coil 28 moves closer to the welding root portion 24.
The bottom echo level begins to decrease as the center reaches the position facing the welding root portion 24, and the bottom echo level shows -5 dB (this corresponds to the reflected echo JiWb in FIG. 5).

The characteristics shown in Fig. 6 @) obtained in the experiment described above have extremely high reproducibility when using the electromagnetic ultrasonic probes 22.23, and therefore each probe 22. 23
The relative position between the welding root portion 24 and the welding root portion 24 can be known.

That is, when the welding part 13 does not reach the welding root part 24,
If the received echo level by the second probe 23 is OdB, then the received echo level by the first probe 22 is -6
Since it exceeds dB (for example, s, s aB), it can be determined by the characteristic curve of FIG.

On the other hand, when the welding part 13 passes the bath contact route part 24, the received echo level by the first probe 22 is less than -6 dB (for example, -6.5 dB), and the characteristic curve shown in Fig. 6 (b) is obtained. You can determine how many layers are exceeded by

From the above, in order to apply this to the automatic welding machine 14, the function based on the characteristics shown in FIG. ．． By comparing the detection signal corresponding to the amount of reflected echo inputted from the second probe 22, 23 with the function, the deviation between the two can be calculated. Therefore, the teaching program may be corrected based on this deviation, and the welding torch 21 may be operated for playback.

In this way, the welding torch 21 moves along the welding line while being subjected to foot-back control, and an extremely good welded portion 13 can be formed.

In the embodiment of the present invention, the electromagnetic ultrasonic probes 22 and 23 are used as the probes. First, the position of the welded part 13 in a molten state during or immediately after welding is detected. Therefore, the electromagnetic ultrasonic method, which can transmit and receive ultrasonic waves without contacting the core material Ti, is effective. This is because the bottom echo level obtained is very stable, making it possible to increase the reliability of detected values. However, the vertical ultrasonic probe in the present invention is not limited to the electromagnetic ultrasonic probes 22 and 23 described above, and may be an ultrasonic probe using a magnetostrictive vibrator, a piezoelectric vibrator, an electrostrictive vibrator, etc. It may also be used as a probe, and good results can also be obtained using these.

Furthermore, in the embodiment of the present invention, it has been described that the first probe 22 is disposed directly below the weld root portion 24, which is the optimum penetration tip position of the weld J3.
It may also be arranged directly below the weld toe 29 which is the contact point between the base metal work 1 and the weld toe 29 to detect the optimum penetration toe position of the weld 13.

Further, in the embodiments of the present invention, the horizontal base metal 11 and the vertical base metal 12 are T-joint welded, but the present invention is not limited to this, but can also be applied to butt welding, butt welding, lap welding, etc. On the other hand, when the welded portion is on the lower surface of the base material, it is sufficient to arrange the probes 22 and 23 on the upper surface of the base material.

The welding part detection device using ultrasonic waves according to the present invention is as described in detail above, and therefore has the following effects.

■ In conventional technology, when detecting the penetration position of the weld root or weld toe, the probe was scanned in parallel with the linear movement of the welding torch.
In the present invention, since the probe can be moved linearly in the same way as the welding torch, an automatic welding machine or a welding logget can be realized with a simple configuration, and teaching operations can be easily performed during handling.

However, in the present invention, since the probe can be moved in the direction of the weld line, it is possible to continuously detect the penetration position of the weld.

■ Position the probe directly below or above the welding torch,
Because it can make the same movement as the welding torch,
By detecting the weld root or weld toe during melting and controlling the welding torch by feeding back the detection signal to the welding torch, it is possible to create a weld with an ideal penetration state. can be formed.

[Brief explanation of the drawing]

Figures 1 to 3 show a conventional weld detection device, with Figure 1 being an explanatory diagram of its principle, and Figure 2 showing the reflections at the probe positions A, B, C, and D in Figure 1. A characteristic diagram showing the amount of echo, Figure 3 is an explanatory diagram of the operation, Figure 3 (0) is a plan view of the base material, Figure 3 (p) is a bottom view of Figure 3 (A), and Figures 4 to 4 are diagrams showing the amount of echo. Figure 6 shows the welding part detection device according to the present invention, Figure 4 is its overall configuration diagram, Figure 5 is a characteristic line diagram showing the amount of reflected echoes, Section 6 is an explanatory diagram showing the bottom echo level, and Figure 4 is a diagram showing the overall configuration thereof. FIG. 6(A) is an explanatory diagram showing a method of measuring the bottom echo level using a transmitting/receiving coil, and FIG. 6 (←) is a diagram showing the characteristics of the bottom echo rail. 11.12...Base metal, 13...Welded part, 14...
Automatic welding machine, 21... Welding torch, 22.23...
Electromagnetic ultrasonic probe, 24... Welding root part, 25...
- Flaw detection device, 26... Arithmetic processing device, 29... Weld toe. Patent applicant: Hitachi Construction Machinery Co., Ltd. Hitachi, Ltd. Figure 1 Figure 2 Figure 3 Figure 7, -〇

Claims (1)

[Scope of Claims] (1) In an ultrasonic weld detection device that detects the penetration position of a weld by projecting ultrasonic waves onto the weld formed between base metals, the penetration position is Inspect ~
The first thing to do is. a second ultrasonic probe; and a moving means for moving each of the probes together with a welding torch along the welding line direction between the base metals; A welding part detection device using ultrasonic waves, characterized in that a second probe is arranged at a position facing the direct part in a molten state, and a second probe is arranged at a position facing the base material separated from the welding part. (2)
The first probe is disposed at a position facing the weld root or weld toe of the weld.
1) The ultrasonic weld detection device described in item 1). (3) Above 1. An ultrasonic weld detection device according to claim 1, wherein the second probe is an electromagnetic ultrasonic probe.